1. Field of the Invention
The present invention relates to an image recording apparatus, especially a recording apparatus using a photo curable ink which is cured by photo irradiation.
2. Description of Related Art
In an image recording apparatus in which a small ink droplet is discharged from a recording head and landed onto an recording medium which is placed to face with the recording head so that an image is recorded. There are problems such as drag and blur of ink due to uncuring and unfixing of ink when an image is recorded onto a recording medium having poor absorbability of ink.
In order to solve the above problems, a method to perform a suitable recording and fixing of an image is known, where photo curable ink containing a photo initiator sensitive to light such as ultraviolet is used and light is irradiated to the ink landed on the recording medium by a light irradiating device.
In curing and fixing ink, sensitivity of photo curable ink, timing of light irradiation, wavelength and intensity of the light and the like are factors which especially affect to image quality. Problems such as dot diameter and blur become more prominent as time goes by after landing of the ink. Thus, it is preferable the time interval between ink discharge and light irradiation is as short as possible.
For example, JP Tokukaisho 60-132767A discloses an inkjet printer provided with a curing and fixing member of landed ink, which is an ultraviolet irradiation lamp having sufficient length to irradiate approximately overall width of an recording medium which is installed fixedly on a side where the recording medium is ejected with regard to an inkjet recording head, and also discloses an inkjet printer of a serial print type in which an inkjet recording head moves in a width direction of the recording head, and an ultraviolet lamp is provided on at least one side of the recording head.
Generally, a light irradiating device using a high pressure mercury lamp as a light source is provided with a cooling device which cools the light irradiation lamp as a measure for heat. In order to prevent a problem that air flow generated by blowing of the cooling device interferes landing of ink discharged from a recording head, silica glass is provided at light irradiation aperture of the light irradiating device so that air flow toward the recording head is eliminated.
JP Tokukai 2003-165208A mentions a measure for heat of an ultraviolet irradiation lamp, and discloses an inkjet recording apparatus provided with an inkjet recording head, a cover of the ultraviolet irradiation lamp and an exhaust duct.
However, In the case that a jam of a recording medium occurs, for example, between a recording medium supporting section and a light irradiating device when a carriage on which the light irradiating device and a recording head are mounted moves for image scanning, a contamination or breakage may occur in case the carriage is very close to the recording medium. In such case, a recording medium may be fused and adheres to silica glass due to heat of the light irradiating device and the uncured ink landed on the recording medium adhere to the silica glass. Furthermore, the recording medium contacting with the light irradiating device may take fire due to heat of the light irradiating device.
On the other hand, for example, it is possible to use a low pressure mercury lamp in which a cooling device is not essentially required for the light irradiating device, in stead of the high pressure mercury lamp. In this case, the silica glass may not be provided to the irradiation surface of the light irradiating device. Therefore, surface of the light irradiation lamp may be contaminated with uncured ink or the light irradiation lamp is broken by contact of the recording medium, due to the jam occurred between the recording medium and the light irradiating device.
Due to the ink adhered to the light irradiating lamp or the silica glass or a flaw formed by the contact caused by the jam interrupts the light irradiated from the lamp so that light irradiation is not sufficiently irradiated to the ink landed on the recording medium. Thus, suitable curing and fixing of the ink is inhibited. Further, in the case a light irradiation lamp having high heating value such as a high pressure mercury lamp is used, it is necessary to prohibit a fire of the recording medium from the viewpoint of safety aspect.